The No.5 seed needed five sets to avoid what would have been an historic upset.

Sabalenka and Gauff look to stay on collision course on Day 4 down under.

No. 8-seeded Emma Navarro rallied from 3-5 down in the decider edging Peyton Stearns 6-7, 7-6, 7-5 in a three hour, 20-minute thriller.

Naomi Osaka asked a friend to retrieve her daughter's birth certificate from her L.A. home before fending off Caroline Garcia 6-3, 3-6, 6-3 in her AO opener.

The 10-time champion got better as the match wore on as he took the legs from his first-round opponent.

The Spaniard opened his bid for a fifth major title with a solid three-set win.

Sinner has won his last 29 sets on the trot, dating back to last October.